We've prepared some molecular wave-functions with Molpro using an ECP (we prefer not to use pseudo-potentials). The wave-function was converted using molden2qmc into the gwfn.data form and CASINO reads it. However, it does not cater for the ECP and we do not know how to do this. From the manual and elsewhere, it seems to be possible. Would anybody be able to tell me how to do it?

For calculations with pseudopotential (ECP) is usually required to have two formats for the pseudopotential (ECP) — one for conventional quantum chemical programs, the other for CASINO. It is also necessary to have a basis corresponding to this pseudopotential (ECP).

You should convert Gaussian format to Molpro first.It is necessary to make sure that the atomic numbers for atoms with a pseudopotential in the gwfn.data file are +200. molden2qmc has an optional argument --pseudoatoms as it cannot detect if a pseudopotential was used, set it to: none = pseudopotential was not used for any atoms in this calculation (default). all = pseudopotential was used for all atoms in this calculation. white space separated numbers = list of pseudoatom's number (started from 1).According to the CASINO manual "7.5 Pseudopotential file" you should rename ECP for C atom in CASINO format to c_pp.data file and place it in the directory where Casino is run, adjust up- and down- electron numbers in the input file, then run CASINO as usual, switch on USE_TMOVE in DMC which is on by default since 2018.

Formats for ECP used by different programs are similar. On the https://bse.pnl.gov/bse/portal you can get the desired potential in various formats but not in Casino.And I do not know how to convert to, but maybe some clues can be found in the directory CASINO/utils/pseudo_converters of the Casino tarball